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  1. #1
    ronlamarsh's Avatar
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    Mixing Microphen

    A question for all the chemical guru's: my microphen formula calls for 3.5g boric acid so the question is, since I don't have any boriuc acid, can one subsititute say sodium bisulfite? And futhermore what is the boric acid actually for since ilford also uses it in perceptol I believe? Can you just leave it out?
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  2. #2
    Ian Grant's Avatar
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    Boric acid is used to buffer the developer alongside Borax.

    Try asking your local chemist/pharmacy as they may have some, it's used in eye baths.

    The Microphen formula (ID-68) only uses 2g of Boric acid so you have an incorrect formula, probably the Ilford PQ variant of D76/ID-11 - if it uses 0.2g Phenidone & 100g Na Sulphite.

    Ian

  3. #3

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    Ron, the only formula that I'm aware of and is supposedly close to Microphen (but not identical) is ID68. It has both borax and boric acid and this combination (AFAIK) acts as a buffer, so it helps to keep the pH of the developer as stable as possible. So, if you leave it out, it will definitely alter the pH of the developer and you'll get something different. Just buy some boric acid and mix the proper formula, it's quite cheap actually. I can find it in drugstores here, it has medical applications. BTW, the fine powder form doesn't dissolve easily, but the crystalline form does.

  4. #4
    Ian Grant's Avatar
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    These are the usual buffers for MQ developers, they'll be the same for PQ

    M.Q. - borax pH 8.6
    M.Q. - buffered borax pH 7·9

    Ian

  5. #5

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    Your drugstore may have two forms of boric acid; powder and crystalline. You need to buy the crystalline form as the powder is hard to dissolve and tends to float on the surface of liquids.
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  6. #6

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    One day I will mix up some ID-68, some Ilford Replenishing Developer and a packet of Microphen and compare the three. In the meantime I have pasted below, for what they're worth, some notes taken from web sites/ mail lists over the years from, among others, Ryuji Suzuki and Richard Knoppow.

    <start of quotes>

    On 11-Feb-2005 Ryuji Suzuki wrote:
    Microphen is a packaged version of Ilford ID-68

    As far as I know they are different developers. Microphen is said to be
    same as an unnumbered Ilfored formula developed for repenished deep tank
    use.


    Some have guessed ID-68 to essentially be Microphen, and others have
    guessed the Ilford Replenishing Developer. Perhaps both guesses are just as
    accurate, the formulas have strong similarities. The best test would be to
    mix all three and develop some film.

    ID-68 IRD
    sodium sulfite 85 g 100 g
    hydroquinone 5 g 5 g
    borax 7 g 3 g
    boric acid 2 g 3.5 g
    phenidone 0.13 g 0.2 g
    potasium bromide 1 g 1 g
    water to make 1 liter 1 liter
    target pH ? 8.95
    >
    The formula for Ilford Replenishing Developer is from page 112 of The Film
    Developing Cookbook. Also given are two replenishers for this developer,
    one for topping up and the other for a bleed system.
    --Michael

    There is a replenisher formula for ID-68. More modern
    developers, like Xtol and T-Max RS are both developer and
    replenisher. For continuous machine use there is often a
    developer starter or developer conditioner as used for color
    developers. This is to insure consistent results from the
    start.
    FWIW, here is the formula for ID-68 replenisher.

    Ilford ID-68R
    Water, at 125F or 52C 750.0 ml
    Sodium Sulfite, dessicated 85.0 grams
    Hydroquinone 8.0 grams
    Borax 7.0 grams
    Phenidone 0.22 grams
    Water to make 1.0 liter

    Ilford's instructions are to add this to the tank to
    maintain the level. This is a crude way of replenishing that
    does not insure consistency.

    I think it would be useful to test all three developers
    but my guess is that there probably isn't a whole lot of
    difference. IRD has much more Phenidone but is buffered to a
    lower pH (ID-68 has more Borax and less boric acid). I think
    the pH in all of these is too low for Hydroquinone to be
    active as a developing agent as is the case with D-76.
    ---
    Richard Knoppow
    ============================================
    Ilford pdf says Microphen pH=8.80+/-0.13
    IRD ph=8.95 according to above, but probably should be lower.
    ID-68 is probably a bit higher (more borax, less boric acid)

  7. #7
    Ian Grant's Avatar
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    Knoppow is often quite wrong, Phenindone and Hydroquinone are super-additivem you can't leave the Hydroquinone out.

    There are a whole series of articles written by Ilford chemists which happen to document the evolution of the Axford/Kendall Commercial PQ Fine Grain developer. They clearly show the evolution from the very early published PQ variant of ID-11(D76) through to the final commercial version "Autophen"

    A 1957 BJP article by P. Brownhill and Jack Coote, both from Ilford, states very clearly that the Axford/Kendal formula is marketed by Ilford as "Autophen"

    When Micropen was released 2 or 3 years later Ilford stated clearly it was "an altogether new type of developer" and they sold both Microphen & Autophen in a variety of sizes, but unlike Microphen Autophen was also available as a powder or liquid concentrate and there were two replenishers as well.

    Knoppow also seems to be unaware that there are two types of replenishment, topping up and bleed, Ilford found that because these PQ developers are very resistant to Bromide build up topping up was sufficient, MQ developers require some developer to be drawn off and when replenishing, which is known as bleed.

    Ilford chemists published another artice on "Soluble Bromides and Phenidone Developers." in 1956.

    It was the Photo Lab Index in the US who mistakenly assumed the Axford/Kendal PQ F.G.F. developer was Microphen, they didn't realise it was Autophen.

    Ian

  8. #8

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    So was Autophen the IRD? When Ilford sold both Autopen and Microphen simultaneously did they have different recommendations for use or suitability? Which published formula is closest to Microphen?

  9. #9
    Ian Grant's Avatar
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    John, Ilford called it PQ F.G.F. in articles before it was released as Autophen, someone else called it IRD, it's also called the Aford/Kendal PQ Fine Grain developer.

    Autophen was designed for Photofinishing machines rather than small scale usage, the recommended development time was 6 mins for machine use with all Ilford roll films, they suggested 8 mins for tank use. They didn't recommend it for tank processing of 35mm film.

    ID-68 is close to Microphen and Ilford recommended using the same developing times.

    The Autophen formula will give a slight speed increase over ID-11(D76) but the ID-68/Microphen formula gives more and is better suited to push processing as well. in practice ID-68 & Microphen are inter changeable.

    In 1960 Microphen was only available in powder form to make 600cc, 2.5, 13.5 & 22.5 litre packaging with just a 2.5 litre Replenisher, while Autophe was available in powder form to make 13.5 & 54 litre and 2 & 4x 54 litre, as a liquid in 4.5 & 22.5 litres (used 1+3, there was a similar large range of replenishers.

    The 13.5 litre powder form of Autophen was 13s 6d while a similar sized pack of Microphen was 25s almost double. That's from my 1960 Ilford Formulae & Packed Chemicals, and it's trade price list.

    Ian



 

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